|Publication number||US7825647 B2|
|Application number||US 12/480,615|
|Publication date||Nov 2, 2010|
|Filing date||Jun 8, 2009|
|Priority date||Jun 19, 2006|
|Also published as||US7557559, US20090243583|
|Publication number||12480615, 480615, US 7825647 B2, US 7825647B2, US-B2-7825647, US7825647 B2, US7825647B2|
|Inventors||Mark S. Olsson, Priscilla S. McLaughlin, Jan Soukup|
|Original Assignee||Seektech, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (3), Classifications (6), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a division of U.S. patent application Ser. No. 11/455,563, which was filed Jun. 19, 2006 now U.S. Pat. No. 7,557,559, and which is as of the filing of this application.
The present invention relates to electronic systems and methods for locating buried or otherwise inaccessible pipes, cables and conductors by detecting an electromagnetic signal emitted by these buried objects.
During construction that involves excavation, it is prudent to determine the actual location of buried pipes, cables, gas lines, AC electric lines, sprinkler wires, CATV cable, communications wiring, and so forth. This is usually done with a portable hand-held locator that senses electromagnetic signals emitted by such buried objects. This is because maps of such buried objects, if they are available at all, are often not complete and/or accurate. Where buried utilities carry an electric signal, such as power lines, often no additional signal need be applied to perform the location. But many pipes and other conduits have no electromagnetic emission that is readily detectable. While a metal water pipe or gas pipe may, for example, re-radiate surrounding electromagnetic signals, the re-radiated signals are weak, and spread over many different frequencies. This makes the location of such buried utilities with a conventional hand-held locator very difficult. A solution is to apply an external signal from an electronic transmitter usually tuned to a specific frequency optimized for the particular application. Hand held locators with antennas, displays and audible tone generators are then used to trace the pipe, whose location is then marked on the ground or pavement with spray paint in a color which indicates whether the pipe carries water or gas, for example. Typically alligator clips attached to leads are used to apply the signal to pipes. A ground spike may be used where access to only one end of the pipe is available for connecting an alligator clip. Many buried utilities and other objects are shielded with insulation or other dielectric coating. Therefore, inductive clamps are used to induce a signal at a predetermined desired frequency without making any direct electrical connection to the metal conductor in the buried utility or other buried object.
Electronic transmitters used in locating buried pipes typically comprise a portable housing with a battery powered signal generating circuit. External jacks are used to connect cords or leads that terminate in an alligator clip or an inductive clamp. A small number of controls are provided, which may include switches for ON/OFF control, mode selection and frequency selection. The housing is usually relatively large and the storage and use of the leads, clips and ground spike are cumbersome.
In accordance with an aspect of the invention, a line illuminator includes a circuit for generating a signal suitable for tracing a buried conductor. First and second leads each have a first end connected to the circuit and a second end connected to a corresponding mechanism for applying the signal to a buried conductor. A case encloses the circuit and is configured for having the first and second leads wrapped around an exterior of the case. Mechanisms are provided for holding the leads wrapped around the exterior of the case.
In accordance with another aspect of the invention a method of locating a buried conductor includes the steps of generating a pseudo sine wave electric signal with a fractional ON time at a predetermined frequency, applying the pseudo sine wave signal to a buried conductor, detecting an electromagnetic signal emitted by the conductor, and determining a location of the conductor from the detected electromagnetic signal.
In accordance with another aspect of the invention a method of locating a buried conductor includes the steps of generating an electric signal having at least one predetermined frequency, applying the signal to a buried conductor, establishing a ground connection using a flexible grounding sheet overlying a surface region above the buried conductor, detecting an electromagnetic signal emitted by the conductor, and determining a location of the conductor from the detected electromagnetic signal.
A case 30 (
Elastomeric bumpers 35 a and 35 b (
The circuit of the compact line illuminator 10 includes a phone jack connector 42 (
A first pair of inverted L-shaped lead hooks 50 and 52 (
Attachment features in the form of upstanding inverted L-shaped flanges 62 and 64 (
A control panel mounted is on the top planar section of the case formed therein. Push button switches 66 and LEDs 68 (
The circuit includes an inductive antenna 71 (
The compact line illuminator 10 can preferably operate in three different modes. In a direct connection mode the alligator clips 22 and 24 are connected directly to a suitable underground target conductor. Where only one end of the underground conductor is accessible, one of the alligator clips 22 or 24 is connected to the ground spike 26 when it is inserted into the ground and functions to provide a return path. Besides the ground spike, other convenient ways of establishing a connection to ground include another pipe, a metal fence post, or a metal sign post. The circuit of the compact line illuminator 10 is preferably capable of dual-frequency transmission, i.e. sending two or more frequencies onto a line simultaneously, in the direct connection mode. In an inductive clamp mode, the jaws of the inductive clamp encircle the target shielded conductor and there is no metal-to-metal contact. In the inductive antenna mode, the compact line illuminator is placed over the buried conductor to be traced and its internal antenna generates a dipole field which energizes the target conductor below ground, inducing a current in the target conductor. No ground connection is needed with the compact line illuminator is operating in its inductive clamp or inductive antenna modes. One example of a locator that can be used to trace underground energized pipes is disclosed in U.S. Pat. No. 7,009,399 granted to Mark S. Olsson et al. On Mar. 7, 2006, and in U.S. patent application Ser. No. 11/077,947 filed Mar. 11, 2005 also of Mark S. Olsson et al., the entire disclosures of which are hereby incorporated by reference.
The compact line illuminator 10 preferably has three available power settings. LOW power provides approximately one-half watt output, MEDIUM power provides approximately two watts output and HIGH power provides approximately five watts output. The LOW power setting provides the least current and therefore the longest battery life.
In order to optimize the power delivered to the load at a frequency the locator can detect, and in order to minimize the generation of harmonic frequencies, the circuit on the PC board 12 preferably generates a stepped approximation of a sine wave which is illustrated in
Establishing a useful ground connection can sometimes be difficult when locating in an area with no available space to attach the ground connection or no soil into which the ground stake can be driven. If a long wire is used to connect to a ground at some location, the long wire can act as an antenna and create another field that can interfere with tracing. Use of metal plates laid onto a flat surface with a clip attached to a bent up edge is problematic. The plates are bulky to store, and worse, they do not conform to uneven surfaces. Simply unwrapping and laying part of one of the leads 18 and 20 on the ground surface will improve signal coupling to some degree. The more length of lead in contact with the surface, the better the capacitive coupling of the signal, which is more effective at higher frequencies.
While we have described an embodiment of our compact line locator, persons skilled in the art will realize that our invention is not limited to this particular embodiment. For example, the inner or proximal ends of the leads 18 and 20 could be connected to the PC board 12 via removable plugs, jacks or other electrical connectors having mating parts attached to the leads 18 and 20 and mounted in one or both of the end cap assemblies 32 and 34. The parts mounted in the end cap assemblies 32 or 34 can be connected to the PC board 12 through wiring inside the case 30. Other means for holding the leads besides hooks could be used such as channels with detents, VelcroŽ straps, straps with snaps, split tubes, clips, bands, pivoting arms, clasps, screw on devices, snap on devices, bayonet locks, ratchet assemblies, and so forth. Other means for holding the batteries can be used besides the tubes, such as frame elements molded into the inner side of the case itself, and slide in battery cradles. The case need not have the flattened tubular configuration, but its rounded sides are advantageous for wrapping the leads and its planar sections are advantageous for mounting the control panel. The case has a relatively low profile and is relatively small. Preferably the case has a width at least twice its height, and a length of at least one and one-half times its width. The compact line illuminator 10 can continuously broadcast status information per Bluetooth, Zigbee or other wireless protocol for receipt by a similarly equipped locator. In this fashion the locator can receive and respond to status information, such as the current operating frequency and power level of the compact line illuminator, and send commands to the compact line illuminator 10 for changing its operating parameters. In such an arrangement, the illuminator does not even need to have any user actuated controls, and therefore the control panel can be eliminated and the illuminator can be turned ON and OFF, and its settings monitored and changed, via controls on the locator using its graphic user interface (GUI). The compact line illuminator 10 need not have any internal antenna and may rely strictly upon direct connection via the leads and alligator clips, or inductive coupling via an inductive clamp. The batteries need not be contained within the case 10 and the circuit could instead be connected to an external power source. Therefore, the protection afforded our invention should only be limited in accordance with the following claims.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|WO2013148714A2||Mar 26, 2013||Oct 3, 2013||Mark Olsson||Ground tracking systems and apparatus|
|WO2015017476A1||Jul 29, 2014||Feb 5, 2015||SeeScan, Inc.||Inductive clamp devices, systems, and methods|
|WO2016003938A1||Jun 29, 2015||Jan 7, 2016||SeeScan, Inc.||Ground tracking apparatus, systems, and methods|
|U.S. Classification||324/67, 324/326|
|International Classification||G01V3/08, G01R19/00|
|May 6, 2014||FPAY||Fee payment|
Year of fee payment: 4
|May 6, 2014||SULP||Surcharge for late payment|
|Aug 8, 2014||AS||Assignment|
Owner name: SEESCAN, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OLSSON, MARK S;MCLAUGHLIN, PRISCILLA S;SOUKUP, JAN;SIGNING DATES FROM 20140519 TO 20140724;REEL/FRAME:033497/0811